After 18 years with the network, Darnell decided not to renew his contract. And he tells TheWrap that the timing of his exit wasn't related to his biggest hit "American Idol's" declining ratings.

"That had nothing at all to do with my decision," he said. "'Idol' is a phenomenon, it's historic."

Darnell led "Idol" to an astonishing eight-year run as the top show on television, which ended only last year when it was bumped by NBC's "Sunday Night Football." It helped inspire a slew of other musical competitions around the globe, including Simon Cowell's "X Factor," which launched a U.S. edition on Fox in 2011.

"When I was a kid, I dreamed of being part of something historic like M.A.S.H.," he said. "Well, now I have. I'm incredibly proud of this show."

In its eleventh year, the show continues to earn enviable ratings, despite its slide since last season. TheWrap reported that talent show would once again be overhauled by letting go of the four judges, among other format changes. But, Darnell said that "nothing has been decided."

"We're still in the very preliminary planning stages," he told us.

Additionally, he concedes that "The X Factor" and "American Idol" compete with each other (as every similar show on TV does), but he doesn't regret bringing the second talent show to Fox.

"First of all, I wasn't going to let Simon Cowell leave the network," Darnell said. "And 'The Voice' was coming whether or not we brought on 'The X Factor.'"

Under his watch, the network took bigger risks on its unscripted fare and saw successes with its Gordon Ramsay culinary franchise, including "Hell's Kitchen." Darnell has many shows he's proud of, but others that have become lessons.

"I'm proud of 'Joe Millionaire' and 'So You Think You Can Dance,' but there have been missteps," he conceded. "'Who's Your Daddy?'"

The 2005 reality show placed an adopted person in a room with 25 men, one of whom, yes, is the person's biological father. Amid low ratings and bad press, Fox canceled the show mid-run.

"A controversial show doesn't get ratings unless the controversy is in the show like fights on 'Real Housewives,' not just about the show like in the case of 'Who's Your Daddy?' Controversy doesn't always drive ratings," he said.

Darnell had been known for having "tacky" tastes — his word, not ours — but said he really can't compete with cable reality shows.

"I saw 'My Strange Addiction' the other day and this woman was eating her mattress," he said.

The outgoing exec has signed on with agency WME, but said he's taking the next few weeks to figure out what he wants to do next.